1. Field of the Invention
A system for detecting the presence of water in an aircraft fuel sump.
2. Description of the Prior Art
As is well known, it is extremely important to make certain that aircraft engines have a continuous supply of fuel free from water. An extremely hazardous situation exists if water accumulates anywhere in the fuel system and freezes to block the flow of fuel.
Sumps are provided at all places on an aircraft where fuel exists from tanks, filters, etc. and at other places where water might collect. Water, which is heavier than fuel, may be entrained in the fuel which is supplied to the aircraft tanks. It also may condense from the air that enters the aircraft tanks as the fuel therein is consumed. Since it is essentially impossible to stop water from entering an aircraft fuel system, it is necessary to remove the water from the fuel system to the maximum extent possible. The presence of water in the fuel system manifests itself most noticeably during engine warmup and taxiing when severe vibrations dislodge droplets of water clinging to metal surfaces in the fuel system and cause water droplets floating on fuel in the tanks to sink. If water collects during taxiing it is desirable for the pilot to know this so that a proper assessment can be made of the situation prior to takeoff and appropriate corrective action taken.
Flight regulations require that the sumps on an aircraft be drained prior to each flight. However, since the sumps drain outside the aircraft it is sometimes difficult for maintenance personnel to determine whether water or fuel is being drained. This is particularly true in wet or windy weather. It is, of course, desirable for a pilot to know after the sumps are drained that all the water has actually been drained so that if further draining is required this can be done prior to flight.